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comparison lisp/hyperbole/kotl/knode.el @ 0:376386a54a3c r19-14

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date Mon, 13 Aug 2007 08:45:50 +0200
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1 ;;!emacs
2 ;;
3 ;; FILE: knode.el
4 ;; SUMMARY: Generic nodes for use as elements in data structures.
5 ;; USAGE: GNU Emacs Lisp Library
6 ;; KEYWORDS: extensions, hypermedia, outlines
7 ;;
8 ;; AUTHOR: Kellie Clark & Bob Weiner
9 ;;
10 ;; ORIG-DATE: 5/1/93
11 ;; LAST-MOD: 14-Jun-95 at 12:45:49 by Bob Weiner
12 ;;
13 ;; This file is part of Hyperbole.
14 ;; Available for use and distribution under the same terms as GNU Emacs.
15 ;;
16 ;; Copyright (C) 1993-1995, Free Software Foundation, Inc.
17 ;; Developed with support from Motorola Inc.
18 ;;
19 ;; DESCRIPTION:
20 ;;
21 ;; DESCRIP-END.
22
23 ;;; ************************************************************************
24 ;;; Public functions
25 ;;; ************************************************************************
26
27 ;;;
28 ;;; Knodes
29 ;;;
30
31 (defun knode:create (contents &optional prop-list)
32 "Return a new knode which stores CONTENTS and optional PROP-LIST."
33 (list 'knode
34 'contents contents
35 'plist prop-list))
36
37 (defun knode:contents (knode)
38 "Return KNODE's contents."
39 (if (knode:is-p knode)
40 (car (cdr (memq 'contents knode)))
41 (error "(knode:contents): Argument must be a knode.")))
42
43 (fset 'knode:copy 'copy-tree)
44
45 (defun knode:is-p (object)
46 "Is OBJECT a knode?"
47 (and (listp object) (eq (car object) 'knode)))
48
49 (defun knode:set-contents (knode contents)
50 "Set KNODE's CONTENTS."
51 (if (knode:is-p knode)
52 (setcar (cdr (memq 'contents knode)) contents)
53 (error "(knode:set-contents): First arg must be a knode.")))
54
55 ;;; ************************************************************************
56 ;;; Private functions
57 ;;; ************************************************************************
58
59 (defun knode:get-attr (obj attribute)
60 "Return the value of OBJECT's ATTRIBUTE."
61 (car (cdr (memq attribute obj))))
62
63 (defun knode:remove-attr (obj attribute)
64 "Remove OBJECT's ATTRIBUTE, if any, and return modified OBJECT.
65 Use (setq object (knode:remove-attr object attribute)) to ensure that OBJECT
66 is updated."
67 (let ((tail obj)
68 sym
69 prev)
70 (setq sym (car tail))
71 (while (and sym (eq sym attribute))
72 (setq tail (cdr (cdr tail))
73 sym (car tail)))
74 (setq obj tail
75 prev tail
76 tail (cdr (cdr tail)))
77 (while tail
78 (setq sym (car tail))
79 (if (eq sym attribute)
80 (setcdr (cdr prev) (cdr (cdr tail))))
81 (setq prev tail
82 tail (cdr (cdr tail))))
83 obj))
84
85 (defun knode:set-attr (obj attribute value)
86 "Set OBJECT's ATTRIBUTE to VALUE and return OBJECT."
87 (let ((attr (memq attribute obj)))
88 (if attr
89 (setcar (cdr attr) value)
90 (setq obj (nconc obj (list attribute value)))))
91 obj)
92
93 ;;; ************************************************************************
94 ;;; Private variables
95 ;;; ************************************************************************
96
97 (provide 'knode)
98